Process for preparing naphthalene-1.4.5.8.-tetracarboxylic acid



Patented Apr. 28, 1931 UETED-STATESV HEINRICH GREUNE, or 'HOCHST-ON-THE-MAIN, GERMANY, nssic-ivon To GENERAL ANILINE Won-3s, me, on NEW YORK, 1\T'. 'Y.,' A conronn'rron or DELAWARE V rnocnss mmmmmm NAPHTHA ENE maarnrimcmaoxxmc ACID No Drawing. Application filed July 5, 1927, Seria1 No. 203,670, and in Germany July 9,1925.

I have found that naphthalene-1.4.5.8- tetracarboxylic acid of the following formula:

HO? coon 1100b 00H r is obtained with a good yield by oxidizing in an appropriate manner the compounds of the probable general formula:

wherein R represents a substituent selected from the class comprising hydrogen, halogen,

hydroxyl, and a cyano group. These compounds are obtainable from acenaphthene and a dicarboxylic anhydride derived from p maleic anhydride by opening up the double bond by the addition of an additive molecule according to the process described in my copending U. S. application Ser. No. 203,669, filed on July 5, 1927. The oxidation can be effected in an acid or alkaline medium by means of bichromate or permanganate.

The following examples serve to illustrate my invention, but they are not intended to limit it thereto: o i i (1) 5 parts by weight of the condensation product of the probable formula:

melting at 180 C.-(')btainablefrom acenaphthene and succinic vanhydrid'e', are dissolved in 100 parts by volume of glacial aceticacid, and to this solution are added by portions at r 7 80 C. 50 parts by weight'of finely powdered 5 sodiumbichromatacare being taken that the temperature does not exceed'90 (lat the beginning. Only after all of thebichromate has been introduced, the whole is further heated for some hourstoboiling in a reflux apparatus, then p'ouredfinto about 800 parts by volume of' cold dilute sulfuric acid and after having allowed the mass to stand in the cold for sometime, the resulting precipitate which has partlya granular form and a some- 05 what yellowish appearance, is filtered by suction. In order topurify it, it is dissolved in a dilutefalkalnheated fora short time on the waterbath' with a small quantitybf potassium permanganate, andafter elimination of the excess of the oxidizing agent, the alkaline filtrate is acidified-with a dilute acid. There. is immediately separated a bodyin the form of colorless needles the properties of which are entirely identical with those of the naphthalene-1.4.5.8-tetracarboxylic acid describedby Bamberger andPhilip in Liebigs Annalender Chemief volume 240, page 182.

(2) 25 parts by weightof the c'ondensa tionproduct of the probable formula:

of the melting point 180 C. obtainable from acenaphth-ene and succinic anhydride, are dissolved in 100 parts byvolume of cold, concentrated sulfuric acid, the solution so pre .pared is poured into -900-parts of ice-water,

.mixture begins to froth. strongly whereupon the reaction soon abates. The mass is maintained for some hours at a temperature of 80 C. to 90 (1, then diluted with some water, filtered by suction and the residue is washed with water. In order to purify the produce it is treated in the manner indicated in example 1; on acidifying the alkaline fil- V trate, preferably after having it again decolwherein R represents a substituent selected from the group consisting of hydrogen, halogen, hydroxyl and a cyano group.

2. The process for preparing naphthalene- 1. l,5.8-tetracarboxylic acidwhich comprises causing sodium bic-hromate to act upon a compound of the following formula:

rho- 0H;

wherein R represents a substituent selected from the group consisting of hydrogen, halogen, hydroxyl, and a cyano group.

so; 3, The process for preparing naphthalene- 1.l.5.8-tetracarboxylic acid which comprises causing an oxidizing agent to act upon a compound of the probable formula:

4. The process for preparing naphthalene 1.4.5.8-tetracarboxylic acid which'comprises causing sodium bichromate to act upon a compound of the probable formula:

In testimony whereof, Iaifiiz my signature. HEINRICH GREUNE. 

